1. Field of the Invention
The present application generally relates to electrical pulse techniques including circuits and systems for generating electric pulses, including the use of an energy-accumulating element discharged through a load by a relatively low voltage transistor and for controlling the discharge. Specifically, the pulse techniques are used for generating variable duration nanosecond pulsed electric fields (nsPEF) for electrotherapy.
2. Description of the Related Art
Surgical excision of a tumor can result in an infection and leave a scar. Furthermore, if there are more tumors, every cancerous tumor should be identified and individually excised by a surgeon. This can be time consuming and expensive, not to mention uncomfortable for patients.
Cancerous tumors that are internal to a patient may be especially difficult to remove, let alone detect and treat. Many patients' lives are turned upside down by the discovery of cancer in their bodies, sometimes which have formed relatively large tumors before being detected.
A “nanosecond pulsed electric field,” sometimes abbreviated as nsPEF, includes an electric field with a sub-microsecond pulse width of between 0.1 nanoseconds (ns) and 1000 nanoseconds, or as otherwise known in the art. It is sometimes referred to as sub-microsecond pulsed electric field. NsPEFs often have high peak voltages, such as 10 kilovolts per centimeter (kV/cm), 20 kV/cm, to 500 kV/cm. Treatment of biological cells with nsPEF technology often uses a multitude of periodic pulses at a frequency ranging from 0.1 per second (Hz) to 10,000 Hz.
NsPEFs have been found to trigger apoptosis in cancerous tumors. Selective treatment of such tumors with nsPEFs can induce apoptosis within the tumor cells without substantially affecting normal cells in the surrounding tissue due to its non-thermal nature.
An example of nsPEF applied to biological cells is shown and described in U.S. Pat. No. 6,326,177 (to Schoenbach et al.), which is incorporated herein by reference in its entirety for all purposes.
The use of nsPEF for the treatment of tumors is a relatively new field. There exists a need for a device with better control over electrical characteristics for safe and effective studies and treatments of cancer in human subjects.